The Preparation And Related Window Application Of Temperature-sensitive Photonic Crystals

With the rapid development of today’s world,the problem of global energy shortage is becoming more and more serious,and the continuous development model of high emission,high pollution and high consumption needs to be changed urgently.As one of the main places for people’s daily activities,buildings account for about30%of the total energy consumption.Windows are the most direct light and heat exchange channels between buildings and the outdoor environment,but their energy-saving effect is poor,especially in summer when the high temperature cannot prevent the irradiation of strong light and the rise of indoor temperature,resulting in additional energy consumption.As a responsive optical material,temperature-sensitive photonic crystals have both high reflection properties of photonic band gaps and temperature-sensitive phase transition properties.They can regulate light and heat with temperature changes,and are expected to be used in energy-saving windows.This paper focuses on the preparation process,temperature-sensitive performance test and window application of two temperature-sensitive photonic crystals.The main contents of this paper are as follows:（1）The preparation process of temperature-sensitive PNIPAM hydrogel photonic crystals was studied and its temperature-sensitive properties were tested.Using polystyrenemicrospherecolloidalcrystalsastemplatesand poly-N-isopropylacrylamide（PNIPAM）as temperature-sensitive materials,hydrogel photonic crystals were prepared.In the variable temperature test,the optical properties of the structure changed from high reflection at the photonic band gap to low reflection and low transmission in the whole waveband when the temperature rose to 33℃,and the position of the photonic band gap was blue-shifted.In the experiment,the polystyrene microsphere template was prepared by the vertical deposition method,and the temperature-sensitive PNIPAM hydrogel was successfully prepared by the in-situ polymerization method,and the low critical solution temperature of the PNIPAM hydrogel was determined by the swelling degree experiment.is 33℃.The PNIPAM hydrogel photonic crystal was prepared by immersing the polystyrene microsphere template into the hydrogel.In the variable temperature test,it was found that the photonic band gap would move due to the temperature-sensitive volume swelling of the PNIPAM hydrogel,and the reflection spectrum of the structure It will vary between high reflection in the local band at low temperature and low reflection and low transmission in the whole band at high temperature.During the heating process,the reflectivity at the photonic band gap drops by 47%around 33℃,with the largest change.The above phenomena show that the PNIPAM hydrogel photonic crystal has good temperature response characteristics.Laminated PNIPAM hydrogel photonic crystals were prepared by dry stacking assembly method,which changed from single-layer high reflection in single-band structure to dual-band high reflection,and both were modulated by temperature,which broadened the temperature-sensitive control band.（2）The preparation process of VO₂thin film and VO₂photonic crystal was studied,and its optical properties were explored.In the experiment,the electrochemical deposition method was used to prepare the VO₂thin film.The 1:1alcohol aqueous solution with p H value of 2.0 and ion concentration of 0.15M/L VOSO₄was used as the electroplating solution,and the constant potential of 1.4V was used in a water bath at 30℃.The V₂O₅thin film can be obtained by the reaction,and then annealed at 510℃for 90min in the Ar atmosphere to obtain the VO₂thin film.Using polystyrene microspheres as templates,VO₂photonic crystals were prepared by the process of VO₂film.The templates were pretreated by atomic layer deposition method and high temperature heating method respectively to reduce the phenomenon of colloidal template falling off in electrochemical deposition.Experiments show that the periodic ordered structure of vanadium oxide with small area can be obtained by high temperature heating method,but the area of VO₂photonic crystal obtained after annealing treatment is still relatively limited.The inverse and transmission optical properties of VO₂film and VO₂photonic crystal are studied by electromagnetic simulation.The transmittance of VO₂film to visible light is high,which is higher than 60%in the wavelength band,and the reflectance is generally lower than 10%.The effect of phase transition is small;during the transition of VO₂from the semiconductor phase to the metal phase,the transmittance of the film to infrared light decreases and the reflectance increases.At the wavelength of 2500nm,the transmittance decreases by 69.9%and the reflectance increases by 72%,the above phenomenon shows that VO₂has a strong temperature-sensitive response in the near-infrared region.（3）The window performance of PNIPAM hydrogel photonic crystal and other structures was tested to analyze its energy saving effect.A temperature test device was built using the PNIPAM hydrogel photonic crystal as a window,which proved that the PNIPAM hydrogel photonic crystal can slow down the temperature rise rate of the enclosed space,stabilize the indoor temperature,and block the transmission of light energy after the phase transition of temperature rise.The light and heat regulation performance is better.In the experiment,a simulated window for testing temperature and illuminance was built,and PNIPAM hydrogel,PNIPAM hydrogel photonic crystal and laminated PNIPAM hydrogel photonic crystal were used as window materials,respectively,and light irradiation with different powers and wavelengths was recorded.The changing law of temperature and illuminance inside and outside the window.The research shows that the PNIPAM hydrogel can modulate the light of all wavelengths at high temperature.Compared with the hydrogel window before the phase transition,the hydrogel window after phase transition can reduce the transmission of light by about 72%,and can maintain The room temperature is around33℃,slowing down the heating rate;when the wavelength of the incident light matches the center of the photonic band gap,the photonic band gap can reduce the transmission of light by about 27.1%,and the indoor temperature can be further regulated and stable.temperature.The mathematical model of blocking ratio is established,and the comprehensive analysis shows that the energy saving effect of the laminated PNIPAM hydrogel photonic crystal window is the best.